Iris diaphragm



Jan. 9, 1968 R. J. WQLLENSAK ET AL 3,362,313

IR I S D IAPHRAGM Filed Feb. 23, 1965 United States Patent O 3,ss2,313IRIS DIAPHRAGM Richard J. Wollensak, Rochcster, and `loel W. Graftley,West Henrietta, N.Y., assignors to Minnesota Mining and ManufacturingCompany, St. Paul, Minn., a corporation of Delaware Filed Feb. 23, 1965,Ser. No. 434,304' 8 Claims. (Cl. 95-64) ABSTRACT OF THE DISCLOSURE Thereis disclosed an iris diaphragm structure, especially suitable forlocations subject to severe shock and impact, comprising an annularmetal housing having a cylindrical fiange and a radial flange projectinginwardly from one end of the cylndrical flange and formed integrallytherewith, and an Operating ring rotatable Within the cylindrical fiangeand spaced aXially from the radial fiange. The diaphragm .leaves aremounted between the radial flange and the Operating ring, each leafhaving near one end a pin projecting into a hole in the radial fiange,and near the other end a pin projecting into a radial slot in theOperating ring. Alternate leaves are made of different materials, eg.,brass and stainless steel.

This invention relates to a diaphragm, and more particularly to an irisdiaphragm for controlling the passage of light in an optical system.

An object of the invention is the provision of a generally improved andmore satisfactory diaphragm.

Another object is the provision of a diaphragrn which is particularlyrugged and sturdy, and able to withstand severe shocks and impactswithout dam-age to the parts and also without substantial deflection ofthe diaphragm leaves.

A further object is the provision of a diaphragm sufficiently sirnpie tobe capable of production at minimum expense, and sufficiently rugged tobe satisfactory for use under the severe requirements of militaryservice.

A still further object is the provision of a diaphragm meeting the abovementioned requirements, and yet so 'constmcted that the diaphragm leavescan be adjusted to a different aperture by application of an extremelysmall force, so that the diaphragm is adapted to use with opticalinstruments in which the diaphrag-m is to be adjusted quickly andaccurately by application of for'ces such as those available fromphotocells or other automatic light controlling appliances whichcommonly have a very small output of force.

These and other tlesirable objects may be attained in the mannerdisclosed as an illustrative embodiment of the invention in thefollowing description and in the accompanying drawings forming a parthereof, in which:

FG. 1 is a face view of a diaphragm assernbly according to a preferredembodiment of the invention;

PIG. 2 is an edge 'view of the same;

FIG. 3 is a fragmentary radia-1 section through the same;

FIG. 4 is a face view of a slotted Operating ring constituting part ofthe assembly;

FIG. 5 is a face view of one and PIG. 6 is an edge view of the diaphragmleaf.

Many kinds of iris diaphragms are well known in the art. Most of thosealready known are designed, however, for use on cameras, enlargers, andsimilar instruments in locations where they are not expected to besubject to any great amount of shock or impact, and consequently theycan be and often are rather' delicate in construction.

As distinguished from the diaphragms of the prior art,

of the diaphragm leaves;

the diaphragm of the present invention is especially intended forlocations where it is subject to great shock and impact, and is sodesigned that'it can withstand such shock and impact repeated a greatmany times, Without permanently springing or distorting any of the partsof the diaphragm, or otherwise damaging it. Thus the present diaphragmis particularly adapted and useful for military installations, Where thediaphragm may, for example, constitute part of optical apparatus whichis mounted either directly on or closely adjacent to the barrel of alarge caliber gun. In such a location, each time the gun is fired, thereis a severe shock and impact transmitted to the diaphragm and otherparts of the optical apparatus mounted on or near the gun.

For a military installation such as this, extreme reliability isrequired. In addition, in certain types of military optical apparatus itis essential that the temporary deflection of the adjustable leaves ofthe diaphragm in an axial direction, as a result of a shock or impact,shall not exceed a predeterrnined very small amount, because thediaphragm assembly may be mounted in a location where the leaves of thediaphragm are very close, in an axial direction, to some other delicatepart of the optical system in which the diaphragm is used. Each time thegun is fired the leaves of the diaphragm Will tend to deflect in anaxial direction, but this deflection must be so small that the leaveswill not engage the closely adjacent parts of the optical apparatus. Allof these requirements above outlined are satisfied by the diaphragm ofthe present invention.

The diaphragrn comprises a housing or casing indcated in general at 11,preferably integrally made from a single piece of stainless steel andhaving a circular cylindrical fiange portion 11a at its periphery, andan annular flange portion 111) extending radially inwardly from one endof the cylindrical portion 11a. The end of the housing at which theannular fiange 1117 is located may, for convenience of description, becalled the front of the housing, although obviously the diaphragmassembly may be faced in either direction, depending upon therequirements of the optical system in which' it is used.

A slot 13 extends through the thickness of the cylindrical part 11a ofthe housing, as shown in FIG. 3, and is elongated in a circumferentialdirection as shown in FIG. 2. An internal radial shoulder 15 is formedin the cylindrical fiange 11a, near the front thereof (that is, near theright hand end of the fiange, when viewed as in FIG. 3) so that theinternal diameter of the cylindrical part is slightly smaller to theright of the shoulder 15 than it is to the left of such shoulder. Nearthe rear end (or left hand end when viewed as in FIG. 3) an internalgroove 17 is formed in the fiange 11a. As will be observed in FIG. 3,the shoulder 15 is a little to the right or forwardly of the forwardedge of the slot 13, and the groove 17 is a little to the rear or leftof the rear edge of the slot 13.

Between the shoulder 15 at the front and groove 17 at the back, theinner surface of the flange 11a is smooth and of uniform diameter,except for the presence of the circumferential slot 13. In this smoothportion of the flange 11a, there is rotatably mounted a diaphragmoperating ring 21, made preferably of stainless steel. This ring is ofannular form, and the outer peripheral surface is relieved or cut awayin a continuous circumferential band extending through most of the axiallength of the ring, as shown at 23, but leaving a rim portion 25 of thefull diameter of the ring at the forward end thereof, and anothersimilar rim portion 27 of the full diameter of the ring at the rear endthereof, as well seen in FIG. 3. The rim portions 25 and 27 riderotatably on the inner face of the cylindrical flange ila of the casingor housing, throughout the entire periphery of the inner face.

In those portions of the periphery where the slot 13 is located, thebearing rim 25 is slightly forwardly of the slot 13, and the bearing rim27 slightly to the rear thereof. Between the bearing rim portions 2d and27, where the ring 21 is relieved or cut away as at 23, it is slightlyspaced from the inner face of the housing flange 11a, to provideclearance so as to minimize any friction which might be caused by slightirregularities of the surfaces of the parts.

To the rear of the Operating ring 21 is a resilient split retaining ring31, preferably of stainless steel, seated in the circumferential groove17. The split ring extends around most Of the circumferential length ofthe groove 17, but with enough clearance between the ends of the ring sothat the ring may be contracted enough to pass through the Opening atthe rear end of the cylindrical fiange 11a, and it will then expandresiliently to seat itself in the groove 17, thereby holding theOperating ring 21 in place. The dimensions of the various parts are suchthat the Operating ring 21 has a snug but freely rotatable fit withinthe housing, held against forward displacement in the housing by theshoulder and held against rearward displacement by the split ring 31.

In the space between the front face of the Operating ring 21 and therear face of the annular flange 11h, the diaphragm leaves (sometimescalled blades) are mounted. In the present construction, the leaves maybe of any desired even number. A convenient number of leaves is 12, ashere shown, individual leaves being shown at 35. As best seen in FIG. 5,each leaf is of arcuate shape, approximately Semi-circular in extent,and each has at one end a forwardly extending pivot stud 37, and at theOther end a rearwardly extending Operating stud 39.

The stud 37 of each leaf extends forwardly into snug but rotatableengagement with a circular hole 41 formed through the thickness of thefront flange 11h of the housing. There are several such holes 41, onefor each of the individual iris diaphragm leaves 35, so Vthat if thereare 12 leaves, there will be 12 of these holes 41 spaced evenly aroundthe flange 11h as seen in FIG. 1.

The Operating stud 39 on each leaf 35 extends rearwardly and engagessnugly but slidably in a slot 1115 formed radially in the front face ofthe Operating ring 21. Just as in the case of the holes 41, there is anindividual slot 4-5 for each diaphragm leaf, so that if there are 12leaves, there will be 12 of these slots 415, spaced evenly around thering 21 as seen in FlG. 4. For ease of manufacture, these slots 45extend radially through the entire radial thiclrness of the ring 21,from its outer peripheral edge to its inner edge.

Those familiar with iris diaphragms will readily understand thatrotation of the ring 21 within the housing or casing 11 will move therespective ends of the respective iris diaphragm leaves 35 which havethe pins 39 extending into the slots 45, swinging the respective leaveson their pivots 37 at their opposite ends, with the result that theaperture formed collectively by the inner curved edges of theoverlapping iris diaphragm leaves is made larger or smaller, as the casemay be, depending upon the direction of rotation Of the control ring 21.PIG. 1 illustrates the leaves adjusted to give minimum aperture. Whenthe Operating ring 21 is turned to its opposite limit of motion, to givemaximum aperture, the inner curved edges of the various leaves aresubstantially fiush with the inner edges of the Operating ring 21 and ofthe front flange 11h, so that the aperture defined by the leaves whenVadjusted for maximum aperture is of substantially the same size as theinner edge of the flange 11h and of the operating ring 21.

The rotary movements of the Operating ring 21, to adjust the size of theaperture, are caused in any suitable way, for example by force appliedto a radial stud screwed into a radial threaded opening 51 in the ring21 and extending out through the circumferential slot 111 13. Such astud may be conventional, and is not shown in the present drawingsbecause it is not necessarily part of the diaphragm assembly as suppliedby the manufacturer of the assembly to the concern which is to mount itand use it in a suitable optical system. The circumferential length ofthe slot 13 is sulficient, of course, to allow the radial stud to movecircumferentially to turn the ring 21 to the desired extent from maximumto minimum aperture and vice versa.

A locating stud 53 preferably projects from the front face of the flange11h of the housing 11, in a predetermined position, in Order that whenthe diaphragm assembly is mounted in the optical instrument with whichit is to be used, the locating stud 53 may engage in an Opening in theoptical instrument, thus locating the diaphragm assembly in a particularposition or oricntation.

One of the important features of the present invention is that adjacentdiaphragm leaves 35 are of materials which differ from each other forthe sake of more easy manipulation. Preferably alternate diaphragmleaves 35 are of stainless steel, for example stainlcss steel ofso-called type 303, while the other diaphragm leaves, alternating withthe stainless steel ones, are of brass, for example brass of so-calledtype 70-30. Both the brass leaves and the stainless steel leaves are ofthe same Shape and dimensions, having for example a thickness of 0.003of an inch.

It has been found by test that this preferred construction of stainlesssteel leaves a'lternating with brass leaves provides a diaphragm whichis particularly able to withstand the severe shocks and impacts abovementioned, and works smoothly With minimum power requirements foradjusting the diaphragm from one aperture to another. The alternatingstainless steel leaves give the diaphragm leaves, as a whole, sufiicientrigidity so that the leaves will not defiect to an undesirable extent inthe direction of the optical axis passing centrally through thediaphragm assembly, so that even under severe shock in an axialdirection there will not be a defiection which will momentarily carrythe leaves into contact with a closely adjacent part of the opticalapparatus. A diaphragm constructed as here disclosed, in which thehousing has an external diameter of about 1.260 inch and the openingsthrough the housing and through the ring 21 have internal diameters ofabout 0.850 of an inch, has proven particularly satisfactory. In tests,it has successfully withstood repeated impact shock loads of themagnitude of 500 G. No physical damage or permanent deformation ofcomponents has occurred, and the iris leaves have exhi-bited only veryslight instantaneous axial deflection. i

The alternating brass leaves prevent the stainless steel leaves fromrubbing on each other, and prevent them from Hseizing Or sticking toeach other, the brass leaves moving Over the adjacent stainless steelleaves more easily than two stainless steel leaves rubbing on eachother, and more easily than two brass leaves rubbing on each Other.Moreover, all of the leaves (both the brass ones and the stainless steelones) are preferably lubricated, at the time of manufacture, bymolybdenum disulphide, applied in the form of a dry powder rubbed Ontothe surfaces of each leaf and then excess powder removed. Sufiicientpowder remains on the surface of each leaf to lubricate it to anappreciable extent. lt is found that the assembly of the variousdiaphragm leaves, when made of the alternating stainless steel and brassconstruction above described and when luhricated as above described, canbe adjusted with extremely small exertion of circumferential force ortorque to turn the Operating ring 21. Hence the construction is wellsuitcd for use in Optical apparatus where automatic Operating means ofrelatively low power is connected to the ring 21 to turn the ring toadjust the diaphragm aperture from time to time to Various differentapertures.

It is seen from the foregoing disclosure that the objects and purposesof the invention are well fulfilled. It is to be understood that theforegoing disclosure is given by way of illustrative example only,rather than by way of lmitation, and that without departing from theinvention, the details may be varied within the scope of the appendedclaims.

What is claimed is:

1. An iris diaphragm for controlling passage of light, comprising ametallic casing having a substantially cylindrical portion and aninwardly extending radial flange at one end of said cylindrical portion,means forming an internal circumferential groove in said cylindricalportion at a location spaced axially from said radial flange, aninternal circumferential shoulder in said cylindrical portion at alocation between said flange and said groove and spaced aXially fromboth of them, said shonlder being faced toward said groove, a resilientretaining ring seated in said groove, an Operating ring rotatablymounted within said cylindrical portion of said casing and havingperipheral bearing enga-gement with the inner surface of saidcylindrical portion and having axial bearing engagement with saidshoulder and said retaining ring and being retained thereby againstsubstantial aXial movement in either direction, said Operating ringhaving a series of substantially radial slots formed in the face thereofwhich is faced toward said radial flange of said casing, and a series ofdiaphragm leaves mounted in overlapping relation to each other in thespace between said Operating ring and said radial flange, alternate onesof said leaves being of steel and the other leaves being of brass, eachleaf being of elongated curved shape and having substantially at one enda pivot stud projecting forwardly and rotatably seated in an opening insaid radial flange of said casing and having substantially at its otherend an Operating stud projecting rearward'ly and seated in one of saidradial slots in said Operating ring, so that rotation of said operatngring within said casing will move said leaves to vary the size of theaperture defined by the collective leaves.

2. A construction as defined in claim 1, in which the snrfaces of saidleaves which engage each other are coated with molybdenum disulphide.

3. A construction as defined in claim 1, in which said operating ring isrelatively thick in an axial direction and has a periphery which isrelieved circumferentially in a location intermediate its length so thatits periphery bears on said cylindrical portion of said casing only atspaced locations substantially at the front and rear edges of theperiphery of the ring.

4. A construction as defined in claim 3, in which said ring has asubstantially radial bore extending inwardly from its periphery so thatan Operating stud may be seated in said bore, and in which saidcylindrical portion of said casing has a circumferentially elongatedslot opposite said bore so that an Operating stud seated in said boremay extend out of said casing through said slot.

5. An iris diaphragm assembly for controlling passage of light,comprising a generally cylindrical housing having an inwardly extendingradial flange in fixed position, said flange having a central openingfor passage of light along an optical axis, an Operating ring rotatablewithin said housing about said optical aX'is as a center and spacedaxially from said flange, a series of holes in said flange, a series ofslots in said ring, and a series of iris diaphragm leaves mounted inoverlapping relation to each other in the space between said flange andsaid ring, each leaf having adjacent one end a pivot stud pivotallyengaged in one of the holes in said flange and having adjacent its otherend an Operating stud slidably engaged in one of the slots in said ring,there being an even number of said leaves, alternating ones of saidleaves being of hard and relatively rigid metal, and the intermediateleaves being of softer and more fleXible metal.

6. A construction as defined in claim 5, in which alternate leaves areof stainless steel and intermediate leaves are of brass.

7. A construction as defined in claim 6, in which the surfaces of theleaves which contact with each other are coated with molybdenumdisulphide.

8. An iris diaphragm assembly for controlling passage of light,comprising a generally cylindrical housing having an inwardly extendingradial flange in fixed position, said flange having a central openingfor passage of light along an optical axis, an Operating ring rotatablewithin said housing about said optical axis as a center and spacedaxially from said flange, said Operating ring being relatively thick inan axial direction and having a periphera-l edge formed to providecircumferential bearing ridges substantially only at the forward andrear edges of said ring, to make rotary bearing contact with saidhousing, the portion of said peripheral edge between said bearing ridgesbeing relieved and out of contact with said housing, a series of slotsin said ring, a series of holes in said flange, and a series of irisdiaphragm leaves mounted in overlapping relation to each other in thespace between said ring and said flange, each leaf being of elongatedarcuate shape relatively narrow in a radial direction as compared withits length in a circumferential direction and having inner and outerarcuate edges which are substantially concentric with each other, eachleaf having a pivot stud pivotally engaged in one of the holes in saidflange and an Operating stud slidably engaged in one of the slots insaid ring, s'uccessive diaphragm leaves being construeted alternately ofsteel and of brass.

References Cited UNITED STATES PATENTS 2,465,578 3/1949 Czarnikow et al.64 2,901,956 9/1959 Werner 95- 64 3,298,295 11/1967 Schlapp 95-64FOREIGN PATENTS 443,006 2/ 1936 Great Britain.

OTHER REFERENCES Uhland: German application 1,016,555, prnted Sept. 26,1957 (KL57a 32/06).

NORTON ANSHER, Primary Examner. I. F. PETERS, Assistant Examner.

